Vibrational overtone spectroscopy of jet-cooled methanol from 5000 to 14000 cm(-1)

Spectra of jet-cooled methanol in the overtone and combination region from 5000 to, 14000 cm(-1) have been obtained by means of infrared laser-assisted photofragment spectroscopy. Many of the observed features are assigned to combination bands of the type nv(1) + v(6), nv(1) + v(8), and nv(1) + v(6) + v(8) (n = 1,2,3), where v(1) is the OH stretch, v(6) is the OH bend, and v(8) is the CO stretch. These bands show sharp torsion-rotation structure with features as narrow as 0.1 cm(-1). We also observe CH stretch overtones that are weaker than the OH containing combination bands and lack distinct torsion-rotation structure above V-CH = 2. The extent of observed structure on these bands allows us to place limits on the intramolecular vibrational energy redistribution decay rates in the upper vibrational states. We report a global fit of the observed band centers to a simple expression involving low-order anharmonicity constants. (C) 2005 American Institute of Physics.